Ultrasonic medical system

ABSTRACT

An ultrasonic diagnostic apparatus  12  outputs echo data to a host controller  20 . In the host controller  20 , a tissue coordinate operation unit  48  computes coordinate information of a tumor  30  using a three dimensional probe  10  as an origin; a probe coordinate operation unit  52  computes coordinate information of the three dimensional probe  10  using, as its origin, an X-ray source apparatus  18  which functions as a reference position; and a combined tissue coordinate operation unit  54  uses the coordinate information of the tumor using the three dimensional probe  10  as its origin and the coordinate information of the three dimensional probe  10  using the X-ray source apparatus  18  as its origin to compute coordinate information of the tumor  30  using the X-ray source apparatus as its origin, and outputs the computed coordinate information to the X-ray source apparatus  18.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ultrasonic medical system, and moreparticularly to an ultrasonic medical system for detecting a targettissue through transmission and reception of ultrasound, and computinginformation regarding the position of the detected target tissue.

2. Description of Related Art

Ultrasonic diagnostic apparatuses are actively utilized in medicaldiagnosis and treatment. Medical methods which use an ultrasonicdiagnostic apparatus so as to specify the position of a tissue to betreated include, as one example, radiation treatment involvingirradiation of cancerous tumors.

In radiation treatment, intense radiation is applied to cancerous tissueto kill the tissue. Because it is desirable to minimize irradiation ofnormal tissue when performing such a radiation treatment, it isimportant that the position of a tumor tissue be precisely ascertainedso as to focus the radiation accurately to the tumor tissue. In order toascertain the tumor position, image diagnosis by means of radiography,CT (Computed Tomography), or MRI (Magnetic Resonance Imaging) isperformed prior to the radiation treatment, so that the position of atumor tissue is ascertained in advance for determining the position orrange for irradiation. With such a method, however, accurate irradiationof a tumor tissue cannot be performed if the position of tumor tissue ismoved due to, for example, shifting of the patient's position or theinfluence of breathing.

In order to overcome the above disadvantage, a radiation treatment inwhich the position of a tissue is ascertained using an ultrasonicdiagnostic apparatus is also proposed. More specifically, in thismethod, radiation is directed toward a tumor tissue as the position ofthe tissue is being detected by an ultrasonic diagnostic apparatus. Forexample, Japanese Patent Laid-Open Publication No. Hei 8-24263 disclosesan apparatus which uses an ultrasonic image for shock wave irradiation.

However, the above method also suffers from a problem. Specifically,since conventional ultrasonic diagnostic apparatuses obtain informationregarding a tissue position using an ultrasonic probe as a reference, itmay be difficult to obtain appropriate information regarding theposition of the tissue, depending on the conditions in which theultrasonic probe is used. For example, in a case wherein a doctor orother health professional holds an ultrasonic probe in their hand so asto detect a movement of a tumor tissue on a display screen of theultrasonic diagnostic apparatus, it is not possible to determine whetherdetected movement is caused by a shift of the tumor tissue itself, or bya shift of the ultrasonic probe while the tumor remains still, or bycombination of such movement.

Because information regarding the tissue position obtained byconventional ultrasonic diagnostic apparatuses is based on theultrasonic probe which functions as a reference as described above,information regarding the position of a target tissue depends on theposition of the ultrasonic probe.

It is therefore an advantage of the present invention to provide anultrasonic medical system capable of outputting appropriate informationregarding the tissue position.

SUMMARY OF THE INVENTION

The present invention was conceived in view of the aforementionedproblems of the related art and provides an ultrasonic medical systemcomprising a wave transceiver for transmitting and receiving ultrasoundwith regard to a space including a target tissue and outputting areception wave signal; first relative coordinate operation means forcomputing first relative coordinate information of the target tissueusing the wave transceiver as an origin, based on the reception wavesignal; second relative coordinate operation means for computing secondrelative coordinate information of the wave transceiver using areference position as an origin; and combined relative coordinateoperation means for computing combined relative coordinate informationof the target tissue using the reference position as an origin, based onthe first relative coordinate information and the second relativecoordinate information, and outputting the combined relative coordinateinformation.

With the above configuration, because the coordinate information of thetarget tissue can be obtained using a desired reference position as anorigin, the coordinates of the target tissue can be specifiedindependently of the coordinates of the wave transmitter/receiver. Forexample, even when the wave transceiver moves or when the coordinates ofthe wave transceiver is not specified, the coordinates of the targettissue can be ascertained as relative coordinates with regard to theknown reference position. In the above configuration, each of the firstrelative coordinate information and the second relative coordinateinformation may be synthesized information regarding a plurality ofcoordinate systems. For example, the second relative coordinateinformation may be coordinate information obtained by synthesis of thesecond (first) relative coordinate information and the second (second)relative coordinate information. Thus, it is possible to compute thecombined relative coordinate information from three or more items ofcoordinate information including the third relative coordinateinformation, the fourth relative coordinate information, and the like,based on the same principle as used for computing the combined relativecoordinate information from the first and second relative coordinateinformation.

Preferably, the wave transceiver transmits and receives ultrasound withregard to a three dimensional space including the target tissue, andeach of the first relative coordinate information, the second relativecoordinate information, and the combined relative coordinate informationis three dimensional relative coordinate information. More preferably,the second relative coordinate information includes position informationand direction information of the wave transceiver using the referenceposition as an origin.

Preferably, the above ultrasonic medical system further includes agenerator which is provided at either one of a measurement origin whosepositional relationship with the reference position is known and thewave transceiver, for generating a measurement signal, and a detectorwhich is provided at the other of the measurement origin and the wavetransceiver, for detecting the measurement signal, and the secondrelative coordinate operation means computes the second relativecoordinate information of the wave transceiver using the referenceposition as an origin, based on the detection result by the detector.With such a configuration in which a non-contact coordinate detectionconfiguration is achieved by the generator and the detector, themovement of the wave transceiver is not limited during coordinatedetection. It should be noted that the measurement signal is a signalused for measuring the coordinates of, for example, the position of thewave transceiver. Preferably, the generator is a magnetic fieldgenerator for generating a magnetic field, and the detector is amagnetic field detector for detecting the magnetic field. With thisconfiguration, because the magnetic field can be detected by themagnetic field detector without being blocked by a human body, it ispossible to maintain the accuracy in computing the coordinates of thewave transceiver irrespective of the body position of a doctor or anexaminer. Further, because magnetic fields and ultrasound do notinteract with each other, influence of the magnetic field generated bythe magnetic field generator on the ultrasound by the wave transceiver,or influence of the ultrasound on the magnetic fields can bedisregarded.

Preferably, the first relative coordinate operation means computes thefirst coordinate information of the target tissue using the wavetransceiver as an origin, based on coordinate information specified byan examiner by using an ultrasonic image formed based on the receptionwave signal.

Preferably, the above ultrasonic medical system further comprises aholder mechanism for holding the wave transceiver and a measurementinformation operation unit for outputting measurement informationregarding the wave transceiver which is held by the holder mechanism,and the second relative coordinate operation means computes the secondrelative coordinate information of the wave transceiver using thereference position as an origin, based on the measurement information.More preferably, the measurement information is coordinate informationof the wave transceiver relative to a measurement origin whosepositional relationship with the reference position is known. Still morepreferably, the holder mechanism is an articulated robot, and themeasurement information is information based on length data and angledata regarding each movable section of the articulated robot. Furtherpreferably, the wave transceiver is brought into contact with a bodysurface of a patient, and the holder mechanism includes a pressuresensor for measuring a contact pressure exerted to the patient by thewave transceiver, for controlling the contact pressure to apredetermined value based on the output from the pressure sensor.

Preferably, the above ultrasonic medical system comprises a radiationsource apparatus for performing irradiation with radiation whilecontrolling an aim based on the combined relative coordinateinformation. With this configuration, it is possible to apply radiationintensely to the target tissue, while minimizing irradiation of tissuesother than the target tissue by controlling an aim such that radiationis accurately applied to the target tissue. Therefore, the tumor can bekilled while irradiation of normal tissues is reduced. As radiation,electromagnetic radiation such as X-rays and gamma-rays, and particlebeams such as proton beams and deuteron beams may be used.

Preferably, the radiation source apparatus controls the aim inaccordance with a movement of the target tissue based on the combinedrelative coordinate information. With this configuration, even when, oreven as, the target tissue moves, it is possible to apply radiationintensively to the target tissue while minimizing irradiation of tissuesother than the target tissue, by controlling the aim such that radiationis accurately applied to the target tissue. Therefore, the tumor can bekilled while irradiation of normal tissues is reduced.

The above ultrasonic medical system may further comprise a punctureapparatus for controlling a puncture position based on the combinedrelative coordinate information. With such a configuration, it ispossible to cause a puncture needle to reach the target tissueaccurately, by introducing the puncture needle while controlling an aimsuch that the puncture is focused on the target tissue.

Further, in accordance with another aspect of the present invention,there is provided an ultrasonic medical system comprising an ultrasonicprobe which is held by a probe holder mechanism for outputting positionand direction information and is brought into contact with a bodysurface of a patient, the ultrasonic probe transmitting/receivingultrasound with regard to a three dimensional space including a targettissue; an ultrasonic diagnostic apparatus for obtaining, via theultrasonic probe, echo data for each of voxels forming the threedimensional space; and a host controller which extracts a voxelcorresponding to the target tissue based on an echo level of the echodata, computes first relative coordinate information of the targettissue using the ultrasonic probe as an origin, computes second relativecoordinate information of the ultrasonic probe using a referenceposition as an origin based on the position and direction information,and computes combined relative coordinate information of the targettissue using the reference position as an origin based on the firstrelative coordinate information and the second relative coordinateinformation and outputs the combined relative coordinate information.

Preferably, the above ultrasonic medical system further comprises aremedial beam source apparatus for performing irradiation with aremedial beam while controlling an aim in accordance with a movement ofthe target tissue based on the combined relative coordinate information.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other advantages of the invention will be explained in thedescription below, in connection with the accompanying drawings, inwhich:

FIG. 1 is a diagram showing a configuration of an ultrasonic medicalsystem according to the present invention;

FIG. 2 is a diagram showing transmission and reception of ultrasoundwith regard to a three dimensional space;

FIG. 3 is a diagram showing a relationship between position vectors inthe present invention;

FIG. 4 is a diagram showing a relationship between coordinate systems inthe present invention;

FIG. 5 is a diagram showing a remedial method utilizing an ultrasonicmedical system according to the present invention;

FIG. 6 is a diagram showing a configuration of an ultrasonic medicalsystem according to another embodiment of the present invention;

FIG. 7 is a diagram showing a relationship between positional vectors inthe present invention; and

FIG. 8 is a diagram showing a remedial method utilizing an ultrasonicmedical system according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described withreference to the drawings.

[Embodiment 1]

FIG. 1 shows the overall configuration of an ultrasonic medical systemaccording to a first embodiment of the present invention. The ultrasonicmedical system shown in FIG. 1 is basically composed of a threedimensional probe (three dimensional echo data capturing probe) 10 whichis a wave transceiver, an ultrasonic diagnostic apparatus 12, a magneticfield generator 14, a magnetic field detector 16, an X-ray sourceapparatus 18 which is a radiation source apparatus, and a hostcontroller 20 including a first relative coordinate operator, a secondrelative coordinate operator, and a combined relative coordinateoperator.

The three dimensional probe 10 includes an array transducer 22, a drivemotor 24 for driving the array transducer 22, and a transducer positiondetector 26 for detecting the position of the array transducer 22. Thethree dimensional probe 10 is capable of transmitting and receivingultrasound 28 with regard to a three dimensional space by causing thearray transducer 22, which transmits and receives ultrasound 28, to beoscillated by the driver motor 24. The array transducer 22, which ismoved to a predetermined position by the drive motor 24, effectselectronic scanning to form a scanning plane S and obtains receptionwave data within the scanning plane. The reception wave data thusobtained by the array transducer 22 and transducer position datadetected by the transducer position detector 26 are output to theultrasonic diagnostic apparatus 12. The array transducer 22 performselectronic scanning for transmitting and receiving ultrasound, with thescanning plane S being moved by oscillating the array transducer 22 bythe drive motor 24, so that transmission/reception of ultrasound 28 isperformed over the range of a scanning space.

FIG. 2 shows transmission/reception of the ultrasound 28 with regard tothe three dimensional space. Referring to FIG. 2, the array transducer22 transmits and receives the ultrasound 28 in the depth direction r andin the electronic scanning direction θ to form the scanning plane S. Thearray transducer 22 is then oscillated in the oscillation direction Φ toform a scanning space V including a tumor 30 which is a target tissueand a central point P of the tumor. It should be noted that the threedimensional echo data obtaining probe according to the presentembodiment may include a two dimensional array transducer, namely atransducer which performs electronic scanning over the range of thescanning space V. Further, a probe is not limited to the threedimensional echo data obtaining probe and may also be a two dimensionalecho data obtaining probe, namely a probe which transmits the ultrasound28 only to the scanning plane S in FIG. 2.

Referring again to FIG. 1, a transmitting beam former 32 in theultrasonic diagnostic apparatus 12 controls a transmission drive signalto be supplied to the array transducer 22 for forming the ultrasound 28via the three dimensional probe 10. A receiving beam former 34 collectsreception wave data supplied from the array transducer 22 for formingecho data. A controller (motor position and transmission/receptioncontrol unit) 36 drives the drive motor 24 for the array transducer 22and also obtains oscillation position data of the array transducer 22from the transducer position detector 26, thereby controlling theoscillation position of the array transducer 22. The controller 36further controls the transmitting beam former 32 and the receiving beamformer 34 to form the ultrasound 28 and collect the reception wave dataof the array transducer 22 at each oscillation position. Morespecifically, the controller 36, by controlling the transmitting beamformer 32, the receiving beam former 34, and the array transducer drivemotor 24, transmits the ultrasound 28 to a desired three dimensionalspace and obtains echo data for each of voxels forming the threedimensional space. The echo data for each voxel is designated with anaddress corresponding to relative coordinates using the threedimensional probe 10 as a reference. The echo data is then written intoa three dimensional memory 40 and is also output to the host controller20. The echo data is simultaneously output to an image forming unit 42within the ultrasonic diagnostic apparatus 12 for forming an ultrasonicimage, which is then displayed in an image display unit 44 in the formof a three dimensional ultrasonic image or the like.

The host controller 20 includes a tissue extraction unit 46 and a tissuecoordinate operation unit 48 which constitute the first relativecoordinate operator, a magnetic field transmission/reception controlunit 50 and a probe coordinate operation unit 52 which constitute thesecond relative coordinate operator, and a combined tissue coordinateoperation unit 54 which is a combined relative coordinate operator. Apart or all of these elements forming the host controller 20 may beincorporated in the ultrasonic diagnostic apparatus 12 or the X-raysource apparatus 18.

The tissue extraction unit 46 extracts the tumor 30 which is a targettissue, based on the echo data within the three dimensional space whichis written in the three dimensional memory 40. In one example extractionmethod, echo levels are previously obtained as echo data, and the echolevels are used to discriminate the tumor 30 from normal tissue. Morespecifically, the echo level for each echo data written in the threedimensional memory 40 is compared with a predetermined level whichcorresponds to a border between the echo levels of the tumor 30 and theecho levels of normal tissues to determine echo data portionscorresponding to the echo levels of the tumor 30 as the tumor 30.Because each echo data is designated with an address corresponding torelative coordinates using the three dimensional probe 10 as a referencebefore the data is written in the three dimensional memory 40 asdescribed above, it is possible to determine the relative coordinates ofthe echo data which corresponds to the tumor 30. However, methods otherthan the above method may be adopted for discriminating the tumor. Forexample, image analysis such as a texture analysis may be used.

The tissue coordinate operation unit 48 computes target tissuecoordinates using the three dimensional probe 10 as a reference, basedon the relative coordinates of the extracted echo data portioncorresponding to the tumor 30 using the three dimensional probe 10 as areference. The target tissue coordinates may be obtained for just thecentral point of the tumor 30 by computing the position of a gravitycenter of the tumor 30 from the outer surface coordinates of theextracted tumor 30 portion. Alternatively, all of the relativecoordinates which have been determined as the tumor 30 may be output asthe target tissue coordinates. Further, a position on the ultrasonicimage of the target tissue displayed on the image display unit 44, whichis designated by the examiner who is observing the ultrasonic image maybe determined as the target tissue coordinates. In any case, thecoordinates of the extracted target tissue use the three dimensionalprobe 10 as a reference, because the ultrasound 28 is transmitted andreceived using the three dimensional probe 10 as a reference. In thefollowing description, a case wherein the coordinates for only thecentral point of the tumor 30 is output as the target tissue coordinateswill be explained.

The magnetic field transmission/reception control unit 50 controls themagnetic field generator 14 mounted on the X-ray source apparatus 18 togenerate magnetic field distribution in a room for measuring informationregarding the position of the three dimensional probe 10. The magneticfield transmission/reception control unit 50 also controls the magneticfield detector 16 mounted on the three dimensional probe 10 to detectthe magnetic field distribution generated within the room. Morespecifically, the magnetic field generator 14 has three magnetic fieldgenerating coils whose axial directions correspond respectively to threedirections which are orthogonal to each other, for generating magneticfield distribution. The magnetic field detector 16 also includes threemagnetic field detecting coils whose axial directions correspondrespectively to three directions which are orthogonal to each other. Themagnetic field generator 14 and the magnetic field detector 16 areconfigured to allow detection of not only information regarding theposition of the magnetic field detector 16 relative to the magneticfield generator 14 but also information regarding the direction of themagnetic field detector 16. The information regarding the position ofthe three dimensional probe 10 (coordinate information) is thus measuredby means of the magnetic field generator 14 and the magnetic fielddetector 16. Information regarding the position and the direction can bedetected using any appropriate known method.

The method of detecting the coordinate information of the threedimensional probe 10 is not limited to the detection method using themagnetic field generator 14 and the magnetic field detector 16 asdescribed above, and any other appropriate methods may be used. Forexample, not just a magnetic field, but light, acoustic waves, or radiowaves may be used for detection. When detection by means of light isperformed, a light signal generator and a light detector are used inplace of the magnetic field generator 14 and the magnetic field detector16, respectively. The light signal generator generates light with adistribution such that the intensity of the generated light is differentat different positions in the room, which is then detected by the lightdetector. At this time, the light detector is fixed on the threedimensional probe 10 at three different points, and, by detecting thepositions of the three points, it is possible to use triangulation tocompute not only position information but also direction informationregarding the three dimensional probe 10. Further, it is obvious thatwhen the generator is mounted on the three dimensional probe 10 and thedetector is mounted at a reference position, it is also possible tocompute the position information and the direction information of thethree dimensional probe 10 with respect to the reference positionaccording to the same principle.

The probe coordinate operation unit 52 computes the position anddirection information of the magnetic field detector 16 using themagnetic field generator 14 as a reference, based on the detectionresult output from the magnetic field transmission/reception controlunit 50. The detection result output from the magnetic fieldtransmission/reception control unit 50 is based on position informationand direction information of the magnetic field detector 16 relative tothe magnetic field generator 14. Therefore, by mounting the magneticfield generator 14 at a desired position, such as at the origin of theX-ray source apparatus 18 for example, and mounting the magnetic fielddetector 16 at the origin of the three dimensional probe 10, it ispossible to directly detect information regarding the position anddirection of the three dimensional probe 10 relative to the origin ofthe X-ray source apparatus 18. Due to the design limitation, however,there are cases wherein the magnetic field generator 14 cannot bemounted at the origin position of the X-ray source apparatus 18 orwherein the magnetic field detector 16 cannot be mounted at the originposition of the three dimensional probe 10. These cases will bedescribed with reference to FIG. 3.

Referring to FIG. 3, a difference vector a 56 indicates a deviationbetween the origin position 58 of the X-ray source apparatus 18 whichfunctions as a reference position for X-ray irradiation and a magneticfield generator position 60 which corresponds to a measurement originfor measuring the position and direction of the three dimensional probe10. Further, a difference vector b 62 indicates a deviation between theorigin position 64 of the three dimensional probe 10 and a magneticfield detector position 66. The detection result output from themagnetic field transmission/reception control unit 50 (see FIG. 1) is ameasurement vector 70 corresponding to a relative position vector of themagnetic field detector position 66 relative to the magnetic fieldgenerator position 60. Further, the coordinate information output fromthe tissue coordinate operation section 48 (see FIG. 1) is an ultrasounddetection vector (the first relative coordinate information) 72corresponding to a relative position vector of the tumor position 68relative to the origin position 64 of the three dimensional probe 10.

Accordingly, in order to obtain a combined vector (combined relativecoordinate information) 69 indicating the tumor position 68 using theorigin position 58 of the X-ray source apparatus as a reference, it isnecessary to compute a probe position vector (the second relativecoordinate information) 71 by adding the difference vector a 56 and thedifference vector b 62 to the measurement vector 70 and then add theultrasound detection vector 72 to the computed probe position vector 71.Because the magnetic field generator 14 and the magnetic field detector16 are fixed to the X-ray source apparatus 18 and to the threedimensional probe 10, respectively, both the difference vector a 56 andthe difference vector b 62 are fixed vectors and can therefore bemeasured prior to the measurement of the position 68 of the tumor whichis a target tissue.

When computing the coordinates of the tumor position 68, by performingcoordinate transformation based on these difference vectors a 56 and b62 which have been measured in advance, it is possible to process theorigin position 58 of the X-ray source apparatus 18 and the magneticfield generator position 60 equivalently and also process the originposition 64 of the three dimensional probe 10 and the magnetic fielddetector position 66 equivalently. In the following description, it isassumed that such coordinate transformation has been performed so thatthe coordinate system having an origin corresponding to the originposition 58 of the X-ray source apparatus 18 matches the coordinatesystem having an origin corresponding to the magnetic field generatorposition 60, and such that the coordinate system having an origincorresponding to the origin position 64 of the three dimensional probe10 matches the coordinate system having an origin corresponding to themagnetic field detector position 66.

Referring back to FIG. 1, the combined tissue coordinate operation unit54 computes coordinates of the target tissue relative to the origin ofthe X-ray source apparatus 18 based on the coordinate information of thetarget tissue with the three dimensional probe 10 being used as itsorigin, which is output from the tissue coordinate operation unit 48 andthe position and direction information of the three dimensional probe 10relative to the origin of the X-ray source apparatus 18 which is outputform the probe coordinate operation unit 52. At this point, it isassumed that coordinate transformation between the magnetic fieldgenerator 14 and the X-ray source apparatus 18 and between the magneticfield detector 16 and the three dimensional probe 10 has been performedin the probe coordinate operation unit 52, as described above. In otherwords, the coordinates having an origin corresponding to the magneticfield generator position and the coordinates having an origincorresponding to the X-ray source apparatus position coincide with eachother, and the coordinates having an origin corresponding to themagnetic field detector position and the coordinates having an origincorresponding to the three dimensional probe position coincide with eachother.

A computation method in the combined tissue coordinate operation unit 54will be described with reference to FIG. 4. Referring to FIG. 4, acoordinate system (X, Y, Z) is a coordinate system which is fixed to themagnetic field generator 14 having an origin at the magnetic fieldgenerator position 60, and corresponds to the coordinate system usingthe X-ray source apparatus 18 as a reference. A coordinate system (x, y,z) is a coordinate system which is fixed to the magnetic field detector16 having an origin at the magnetic field detector position 66, andcorresponds to the coordinate system using the three dimensional probe10 as a reference. Here, the origin of the coordinate system (x, y, z)corresponding to the magnetic field detector position 66 when thecoordinate system (X, Y, Z) is used as a reference, is represented bySo(Xo, Yo, Zo). A point e indicates the position of a tumor which is atarget tissue and is represented by e(xe, ye, ze) relative to thecoordinate system (x, y, z) which is a reference. Further, axes X′, Y′,and Z′ which are parallel to the X axis, the Y axis and the Z axisrespectively, are provided, for which a coordinate system having thepoint So as its origin is represented by coordinate system (X′, Y′, Z′).

The positional relationship between the coordinate system (x, y, z) andthe coordinate system (X′, Y′, Z′) is such that when the coordinatesystem (X′, Y′, Z′) is rotated in the order of X′ axis, Y′ axis, andthen Z′ axis by α degree, β degree, and γ degree, respectively, the X′axis coincides with the x axis, the Y′ axis coincides with the y axis,and the Z′ axis coincides with the z axis. As described above, theinformation regarding the position and direction of the magnetic fielddetector using the magnetic field generator as a reference has beencomputed in the probe coordinate operation unit 52. More specifically,the origin position information (Xo, Yo, Zo) of the coordinate system(x, y, z) relative to the coordinate system (X, Y, Z) and the sixdimensional information of the direction information (α, β, γ) have beencomputed in the probe coordinate operation unit 52. The coordinatetransformation from the coordinate system (x, y, z) to the coordinatesystem (X′, Y′, Z′) can then be expressed by the following expression.

[Expression 1] $\begin{bmatrix}X^{\prime} & Y^{\prime} & Z^{\prime} & 1\end{bmatrix} = {{\left\lbrack \begin{matrix}x & {\quad y\quad} & {z\quad} & 1\end{matrix}\quad \right\rbrack \begin{bmatrix}1 & 0 & 0 & 0 \\0 & {\cos \quad \alpha} & {\sin \quad \alpha} & 0 \\0 & {{- \sin}\quad \alpha} & {\cos \quad \alpha} & 0 \\0 & 0 & 0 & 1\end{bmatrix}}{{\begin{bmatrix}{\cos \quad \beta} & 0 & {{- \sin}\quad \beta} & 0 \\0 & 1 & 0 & 0 \\{\sin \quad \beta} & 0 & {\cos \quad \beta} & 0 \\0 & 0 & 0 & 1\end{bmatrix}{\begin{bmatrix}{\cos \quad \gamma} & {\sin \quad \gamma} & 0 & 0 \\{{- \sin}\quad \gamma} & {\cos \quad \gamma} & 0 & 0 \\0 & 0 & 1 & 0 \\0 & 0 & 0 & 1\end{bmatrix}}}}}$

Further, coordinate transformation from the coordinate system (X′, Y′,Z′) to the coordinate system (X, Y, Z) can be expressed as follows:

[Expression 2] $\begin{bmatrix}X & {\quad Y\quad} & {Z\quad} & 1\end{bmatrix} = {\begin{bmatrix}X^{\prime} & Y^{\prime} & Z^{\prime} & 1\end{bmatrix}\begin{bmatrix}1 & 0 & 0 & 0 \\0 & 1 & 0 & 0 \\0 & 0 & 1 & 0 \\X_{0} & Y_{0} & Z_{0} & 1\end{bmatrix}}$

According to the above expressions 1 and 2, coordinate transformationfrom the coordinate system (x, y, z) to the coordinate system (X, Y, Z)can be expressed as follows:

[Expression 3] $\begin{bmatrix}X & {\quad Y\quad} & {Z\quad} & 1\end{bmatrix} = {{{\left\lbrack \begin{matrix}x & {\quad y\quad} & {z\quad} & 1\end{matrix}\quad \right\rbrack \lbrack T\rbrack}\lbrack T\rbrack} = {{\begin{bmatrix}1 & 0 & 0 & 0 \\0 & {\cos \quad \alpha} & {\sin \quad \alpha} & 0 \\0 & {{- \sin}\quad \alpha} & {\cos \quad \alpha} & 0 \\0 & 0 & 0 & 1\end{bmatrix}\begin{bmatrix}{\cos \quad \beta} & 0 & {{- \sin}\quad \beta} & 0 \\0 & 1 & 0 & 0 \\{\sin \quad \beta} & 0 & {\cos \quad \beta} & 0 \\0 & 0 & 0 & 1\end{bmatrix}}{{\begin{bmatrix}{\cos \quad \gamma} & {\sin \quad \gamma} & 0 & 0 \\{{- \sin}\quad \gamma} & {\cos \quad \gamma} & 0 & 0 \\0 & 0 & 1 & 0 \\0 & 0 & 0 & 1\end{bmatrix}\begin{bmatrix}1 & 0 & 0 & 0 \\0 & 1 & 0 & 0 \\0 & 0 & 1 & 0 \\X_{0} & Y_{0} & Z_{0} & 1\end{bmatrix}}}}}$

Accordingly, using the above coordinate transformation matrix [T], thecoordinate transformation can be performed from the coordinate system(x, y, z) to the coordinate system (X, Y, Z), in other words from thecoordinate system using the magnetic field detector as a reference tothe coordinate system using the magnetic field generator as a reference.

Referring again to FIG. 1, the combined tissue coordinate operation unit54 sets up the transformation matrix [T] based on the informationregarding the position and direction of the magnetic field detector 16(three dimensional probe 10) using the magnetic field generator 14(X-ray source apparatus 18) as a reference, which is output from theprobe coordinate operation unit 52. Then, the transformation matrix isused to transform the coordinate information output from the tissuecoordinate operation unit 48 regarding the position 68 of the tumorwhich is a target tissue with the magnetic field detector 16 (threedimensional probe 10) being used as its origin into the coordinateinformation in the coordinate system using the magnetic field generator14, namely the X-ray source apparatus 18, as a reference. The positioninformation for the target tissue using the X-ray source apparatus as areference 18 which has been thus computed is output from the hostcontroller 20 to the X-ray source apparatus 18.

FIG. 5 shows a remedial method using the ultrasonic medical system shownin FIG. 1. The ultrasonic diagnostic apparatus 12, the three dimensionalprobe 10, the magnetic field generator 14, the magnetic field detector16, and the host controller 20 operate as described above, so that theinformation regarding the position of the tumor 30 with the X-ray sourceapparatus 18 being used as a reference is output from the hostcontroller 20 to the X-ray source apparatus 18. The X-ray sourceapparatus 18 controls an arm unit 76 and an irradiation unit 78 based onthe position information of the tumor 30 such that X-ray is intensivelyapplied onto the tumor 30 located within the body of a patient M.Further, by controlling the aim in accordance with the movement of thetumor 30, it is possible to apply intense X-ray radiation to just thetumor, while minimizing irradiation of normal tissues, even as theposition of tumor moves. When the aim is controlled in accordance withthe movement of the tumor 30, it is desirable to continuously detect thetumor 30 by the three dimensional probe 10 during the X-ray irradiation.In this case, the three dimensional probe 10 may be held by a doctor orother person, or may be fixed to a fixing apparatus which is separatelyprovided for the three dimensional probe 10. When a doctor or other userholds the three dimensional probe 10 for performing X-ray irradiation,certain measures must be taken, such as that the examiner puts on anX-ray protector, for example. Further, although the magnetic fieldgenerator 14 is mounted on a base unit 74 of the X-ray source apparatusin FIG. 5, the location where the magnetic field generator 14 isprovided may be appropriately selected according to the usage situation,and the magnetic field generator 14 may be fixed at another position inthe room.

[Embodiment 2]

FIG. 6 shows the overall configuration of an ultrasonic medical systemaccording to a second embodiment of the present invention. In roughterms, the ultrasonic medical system shown in FIG. 6 includes a threedimensional probe (three dimensional echo data capturing probe) 10 whichis a wave transceiver, an articulated robot 80, an ultrasonic diagnosticapparatus 12, a proton beam source apparatus 90, and a host controller20 having a first relative coordinate operator, a second relativecoordinate operator, and a combined relative coordinate operator.

The three dimensional probe 10 and the ultrasonic diagnostic apparatus12 are the same as those shown in FIG. 1 regarding the first embodiment.More specifically, the ultrasonic diagnostic apparatus 12 transmitsultrasound 28 into a three dimensional space within a patient's body viathe three dimensional probe 10, collects reception wave data forobtaining echo data, and displays a three dimensional ultrasonic imageformed based on the obtained echo data on the image display. Theobtained echo data is also output to the host controller 20.

The articulated robot 80 holding the three dimensional probe 10 moves toa diagnostic position on a surface of the patient's body, and alsochanges the direction of the three dimensional probe 10. The threedimensional probe 10 is attached to a probe attachment 82 and changesits position and direction when drive units 84 a to 84 d are driven. Adrive motor (not shown) is provided in each of the drive units 84 a to84 d for driving arms 85 a to 85 c. The operation of each drive motor iscontrolled by a motor control unit 86. The three dimensional probe 10held by the articulated robot 80 transmits and receives ultrasound 28with regard to the three dimensional space within the patient's bodycontaining the tumor.

The motor control unit 86 controls each drive motor within each of thedrive units 84 a to 84 d based on a user operation. The motor controlunit 86 may control each drive motor such that the arms automaticallyfollow the movement of the tumor. Further, a pressure sensor (not shown)is provided in the probe attachment 82 for detecting the pressureexerted on the surface of the patient's body when the three dimensionalprobe 10 is brought into contact with the body surface and outputtingthe detected pressure to the motor control unit 86. Then, the motorcontrol unit 86 controls each drive motor so as to maintain the pressureexerted onto the surface of the patient's body to a fixed value, forexample, thereby preventing an excessive pressure applied to thepatient. The articulated robot 80 outputs the motor driving informationindicating the drive states of the drive units 84 a to 84 d to the hostcontroller 20.

The motor driving information output from the articulated robot 80 willbe described. Assuming that the disposition location of the articulatedrobot 80 (the central point on the bottom portion of the articulatedrobot 80, for example) is a measurement origin, the drive unit 84 a islocated at a fixed position relative to the measurement origin. Thedrive unit 84 a is connected to one end of the arm 85 a for turning ormoving upward and downward the arm 85 a to thereby set an angle of thearm 85 a. The other end of the arm 85 a is connected to the drive unit84 b. Therefore, the position of the drive unit 84 b relative to themeasurement origin is determined by the length and angle of the arm 85a. Accordingly, based on the motor driving information (the angle dataof the arm 85 a) corresponding to the drive unit 84 a, the articulatedrobot 80 outputs a transformation matrix Ta for deriving the positioncoordinates (Xb, Yb, Zb) of the drive unit 84 b relative to themeasurement origin from the measurement origin coordinates (Xr, Yr, Zr).

The drive unit 84 b is connected to one end of the arm 85 b for movingthe arm 85 b upward and downward. The other end of the arm 85 b isconnected to the drive unit 84 c. Therefore, the position of the driveunit 84 c relative to the drive unit 84 b is determined by the lengthand angle of the arm 85 b. Accordingly, based on the motor drivinginformation (the angle data of the arm 85 b) corresponding to the driveunit 84 b, the articulated robot 80 outputs a transformation matrix Tbfor deriving the position coordinates (Xc, Yc, Zc) of the drive unit 84c relative to the measurement origin from the position coordinates (Xb,Yb, Zb) of the drive unit 84 b.

The position of the drive unit 84 d relative to the drive unit 84 c isdetermined by the length and angle of the arm 85 c. Accordingly, basedon the motor driving information (the angle data of the arm 85 c)corresponding to the drive unit 84 c, the articulated robot 80 outputs atransformation matrix Tc for deriving the position coordinates (Xd, Yd,Zd) of the drive unit 84 d relative to the measurement origin from theposition coordinates (Xc, Yc, Zc) of the drive unit 84 c. Further,because the three dimensional probe 10 turns in accordance with theturning of the drive unit 84 d, the articulated robot 80 outputs, basedon the motor driving information corresponding to the drive unit 84 d, atransformation matrix Td for deriving the coordinates of the originposition (Xs, Ys, Zs) of the three dimensional probe 10 relative to themeasurement origin from the position coordinates (Xd, Yd, Zd) of thedrive unit 84 d. Thus, the transformation matrices Ta, Tb, Tc, and Tdrepresenting the holding state of the three dimensional probe 10 isoutput to the probe coordinate operation unit 52 of the host controller20.

The probe coordinate operation unit 52 then computes the position anddirection of the three dimensional probe 10 relative to the measurementorigin (the disposition location of the articulated robot 80), based onthe motor driving information output from the articulated robot 80. Theposition coordinates (Xs, Ys, Zs) of the three dimensional probe 10relative to the measurement origin is computed by the followingexpression.

[Xs, Ys, Zs, 1]=[Xr, Yr, Zr, 1][Ta][Tb][Tc][Td]  [Expression 4]

wherein Ta, Tb, Tc, and Td are transformation matrices based on themotor driving information output from the articulated robot 80, and (Xr,Yr, Zr) indicates coordinates of the measurement origin.

Here, the direction of the three dimensional probe 10 can be computedfrom the position coordinates (Xd, Yd, Zd) of the drive unit 84 d andthe position coordinates (Xs, Ys, Zs) of the three dimensional probe 10.More specifically, it is possible to obtain the line connecting thesecoordinates (Xs, Ys, Zs) and (Xd, Yd, Zd) and obtain the direction ofthe three dimensional probe 10 along that line. In this manner, theprobe coordinate operation unit 52 computes the position and directionof the three dimensional probe 10 relative to the measurement origin.

The tissue extraction unit 46 and the tissue coordinate operation unit48 in the host controller 20 operate similarly to those in the firstembodiment (see FIG. 1). More specifically, the tissue extraction unit46 extracts a tumor based on echo data within the three dimensionalspace which is output from the ultrasonic diagnostic apparatus 12 fordetermining relative coordinates of echo data corresponding to thetumor. The tissue coordinate operation unit 48 then computes coordinatesof the central point of the tumor using the three dimensional probe 10as a reference.

The combined tissue coordinate operation unit 54 uses the coordinateinformation of the central point of the tumor having an origin at thethree dimensional probe 10, which is output from the tissue coordinateoperation unit 48, and the information regarding the position anddirection of the three dimensional probe 10 relative to the measurementpoint which is output from the probe coordinate operation unit 52, tocompute the coordinates of the central point of the tumor relative tothe origin of the proton beam source apparatus 90. The computationperformed by the combined tissue coordinate operation unit 54 will bedescribed.

FIG. 7 is a diagram for explaining the computation performed by thecombined tissue coordinate operation unit 54. It is assumed that thereference position for proton beam irradiation is an origin position 92of the proton beam source apparatus 90 and that the measurement originfor measuring the position and direction of the three dimensional probeis a bottom central point 94 of the articulated robot 80. Further, aposition vector of the bottom central point (measurement origin) 94relative to the origin position (reference position) 92 is assumed to bea difference vector a′ 96. The coordinate information output from theprobe coordinate operation unit 52 (see FIG. 6) is a measurement vector98 which corresponds to a relative position vector of the originposition 64 relative to the bottom central point 94, and the coordinateinformation output from the tissue coordinate operation unit 48 is anultrasound detection vector (the first relative coordinate information)72 which corresponds to a relative position vector of the tumor position68 relative to the origin position 64 of the three dimensional probe 10.

Accordingly, in order to compute a combined vector (combined relativecoordinate information) indicating the coordinates of the tumor position68 using the origin position 92 of the proton beam source apparatus 90as a reference, it is necessary to first compute a probe position vector(second relative coordinate information) 71 by adding the measurementvector 98 and the difference vector a′ 96, and to then add the computedprobe position vector 71 with the ultrasound detection vector 72. Thedifference vector a′ 96 is a known vector because the state in which thearticulated robot 80 and the proton beam source apparatus 90 arearranged is known. It is therefore possible to measure the differencevector a′ 96 in advance, prior to the measurement of the position 68 ofthe tumor which is the target tissue.

Referring back to FIG. 6, the information regarding the coordinates ofthe tumor relative to the reference position, such as the coordinates ofthe central point of the tumor, which is computed by the combined tissuecoordinate operation unit 54 is output to the proton beam sourceapparatus 90, which then directs proton beams toward the positioncorresponding to the coordinates of the central point of the tumor.

FIG. 8 shows a remedial method using the ultrasonic medical system shownin FIG. 6. The ultrasonic diagnostic apparatus 12, the articulate robot80, and the host controller 20 operate as described with reference toFIG. 6, so that the information regarding the position of the tumor 30relative to the reference position is output from the host controller 20to the proton beam source apparatus 90. Based on the positioninformation of the tumor 30, the proton beam source apparatus 90controls an arm unit 104 and an irradiation unit 106 for applying protonbeams 10 intensively to a tumor 30 within a patient M. Further, theproton beam source apparatus 90 controls the aim in accordance with themovement of the tumor 30, so that proton beams can be intensivelydelivered to just the tumor 30, while irradiation of normal tissues isminimized, even when the tumor moves. It should be noted that while thereference position is set to the origin position of the proton beamsource apparatus 90 in the example shown in FIGS. 6 and 8, the referenceposition may be appropriately selected in accordance with actual usage,such as at a predetermined location in a room in which the treatment isbeing carried out.

In addition, other radiation source apparatuses including a lithotomicapparatus may be used in place of the X-ray source apparatus 18 and theproton beam source apparatus 90 for the remedial method using theultrasonic medical system according to the present invention. It is, ofcourse, possible to use remedial beams other than radiation. A medicalmethod utilizing a puncture apparatus which inserts a puncture needletoward the target tissue may also be used. In any case, control ofvarious remedial beam irradiation or puncture needle insertion isperformed based on the information regarding the position of the targettissue using a desired reference position as an origin.

As described above, according to the ultrasonic medical system accordingto the present invention, appropriate information regarding the tissueposition can be obtained.

While the preferred embodiments of the present invention have beendescribed using specific terms, such description is for illustrativepurposes only, and it is to be understood that changes and variationsmay be made without departing from the spirit or scope of the appendedclaims.

What is claimed is:
 1. An ultrasonic medical system comprising: a wavetransceiver for transmitting and receiving ultrasound with regard to aspace including a target tissue and for outputting a reception wavesignal; first relative coordinate operation means for computing firstrelative coordinate information of the target tissue using the wavetransceiver as an origin, based on an output reception wave signal;second relative coordinate operation means for computing second relativecoordinate information of the wave transceiver using a referenceposition as an origin; and combined relative coordinate operation meansfor computing combined relative coordinate information of the targettissue using the reference position as an origin, based on the firstrelative coordinate information and the second relative coordinateinformation, and outputting the combined relative coordinateinformation.
 2. An ultrasonic medical system according to claim 1,wherein the wave transceiver transmits and receives ultrasound withregard to a three dimensional space including the target tissue, andeach of the first relative coordinate information, the second relativecoordinate information, and the combined relative coordinate informationis three dimensional relative coordinate information.
 3. An ultrasonicmedical system according to claim 2, wherein the second relativecoordinate information includes position information and directioninformation of the wave transceiver using the reference position as anorigin.
 4. An ultrasonic medical system according to claim 1, furthercomprising: a generator which is provided at either one of a measurementorigin whose positional relationship with the reference position isknown and the wave transceiver, for generating a measurement signal, anda detector which is provided at the other of the measurement origin andthe wave transceiver, for detecting the measurement signal, wherein thesecond relative coordinate operation means computes the second relativecoordinate information of the wave transceiver using the referenceposition as an origin, based on the detection result by the detector. 5.An ultrasonic medical system according to claim 4, wherein the generatoris a magnetic field generator for generating a magnetic field, and thedetector is a magnetic field detector for detecting the magnetic field.6. An ultrasonic medical system according to claim 1, wherein the firstrelative coordinate operation means computes the first coordinateinformation of the target tissue using the wave transceiver as anorigin, based on coordinate information specified by an examiner byusing an ultrasonic image formed based on the reception wave signal. 7.An ultrasonic medical system according to claim 1, further comprising: aholder mechanism for holding the wave transceiver; and a measurementinformation operation unit for outputting measurement informationregarding the wave transceiver which is held by the holder mechanism,wherein the second relative coordinate operation means computes thesecond relative coordinate information of the wave transceiver using thereference position as an origin, based on the measurement information.8. An ultrasonic medical system according to claim 7, wherein themeasurement information is coordinate information of the wavetransceiver relative to a measurement origin whose positionalrelationship with the reference position is known.
 9. An ultrasonicmedical system according to claim 8, wherein the holder mechanism is anarticulated robot, and the measurement information is information basedon length data and angle data of each movable section of the articulatedrobot.
 10. An ultrasonic medical system according to claim 7, whereinthe wave transceiver is brought into contact with a body surface of apatient, and the holder mechanism includes a pressure sensor formeasuring a contact pressure exerted to the patient by the wavetransceiver, for controlling the contact pressure to a predeterminedvalue based on the output from the pressure sensor.
 11. An ultrasonicmedical system according to claim 1, further comprising a radiationsource apparatus for performing irradiation with radiation whilecontrolling an aim based on the combined relative coordinateinformation.
 12. An ultrasonic medical system according to claim 11,wherein the radiation is a proton beam.
 13. An ultrasonic medical systemaccording to claim 11, wherein the radiation source apparatus controlsthe aim in accordance with a movement of the target tissue based on thecombined relative coordinate information.
 14. An ultrasonic medicalsystem according to claim 1, further comprising a puncture apparatus forcontrolling a puncture position based on the combined relativecoordinate information.
 15. A ultrasonic medical system comprising: anultrasonic probe which is held by a probe holder mechanism foroutputting position and direction information when brought into contactwith a body surface of a patient, the ultrasonic probetransmitting/receiving ultrasound with regard to a three dimensionalspace including a target tissue; an ultrasonic diagnostic apparatus forobtaining, via the ultrasonic probe, echo data for each of voxelsforming the three dimensional space; and a host controller whichextracts a voxel corresponding to the target tissue based on an echolevel of the echo data, computes first relative coordinate informationof the target tissue using the ultrasonic probe as an origin, computessecond relative coordinate information of the ultrasonic probe using areference position as an origin based on the position and directioninformation, and computes combined relative coordinate information ofthe target tissue using the reference position as an origin based on thefirst relative coordinate information and the second relative coordinateinformation and outputs the combined relative coordinate information.16. An ultrasonic medical system according to claim 15, furthercomprising a remedial beam source apparatus for performing irradiationwith a remedial beam while controlling an aim in accordance with amovement of the target tissue based on the combined relative coordinateinformation.